The Treatment Of Micro-polluted Raw Water By The Suspended Clarifier Combined With Ultrafiltration

The ultrafiltration combined process can effectively reduce the membrane fouling under the premise of ensuring the quality of the effluent water,so it is called the third generation green water purification process.The most commonly used ultrafiltration combined processes in water treatment include coagulation-ultrafiltration,conventional treatment-ultrafiltration and activated carbon-ultrafiltration,etc.These processes add new membrane pools based on existing processes,thereby increasing the floor space and infrastructure costs,or even the combination of ultrafiltration due to water plant conditions.This paper proposes an integrated suspended clarification ultrafiltration tank,which uses the characteristics of coagulation and sedimentation in the same structure as the clarifier tank.Ultrafiltration membrane is placed in the clarification area to further shorten the water purification process,reduce the area,and save construction costs.Overcoming the problem of poor adaptability to the water quality and water quality of the clarifier tank,and the problem of unstable effluent water quality.At the same time,clarifying the contact flocculation action of the active slime layer in the pool improves the removal effect of pollutants,thereby reducing membrane fouling and increasing the water production capacity.In this paper,a simultaneous contrast test between the suspended clarification ultrafiltration process and the coagulation sedimentation ultrafiltration process and the direct ultrafiltration process is conducted.Various micro-polluted raw water and winter low temperature and low turbidity water are treated.Each ultrafiltration combined process is studied for micro-polluted raw water.The effect of purification and the operation of the process were analyzed,and the impact of water quality changes on the combined process membrane contamination was analyzed.The significant influencing factors of membrane fouling were determined by variance analysis and correlation analysis,and the composition of membrane resistance and the type of pollution were determined.The difference between the three different ultrafiltration combinations.The following test conclusions are drawn:(1)From the effects of the three ultrafiltration combined processes on the removal of pollutants,each ultrafiltration combination process has excellent turbidity removal efficiency,the removal rate remains above 99%,and the order of organic matter removal efficiency is: suspension clarification Ultrafiltration process> coagulation sedimentation ultrafiltration process> direct ultrafiltration process,PAN membrane ultrafiltration process is better than the PVDF membrane ultrafiltration process,the three ultrafiltration combined process CODMn and UV254 content showed a follow-up The increase of organic matter concentration in water showed an increasing trend,but the effluent content of suspended clarification ultrafiltration process was less than 1.5mg/L,and less than 3mg/L as stipulated by the national water quality standard.The effluent content of suspension clarifier was significantly less than that of the other two ultrafiltration processes;However,the effect of the three ultrafiltration combined processes on the removal of ammonia nitrogen is unsatisfactory and remains in the range of 10% to 20%.(2)From the perspective of the contamination of the three ultrafiltration process membranes,the relative flux decay of the suspended clarification ultrafiltration process among the tested waters is the slowest,and the flux decay of the coagulation and sedimentation ultrafiltration process and the direct ultrafiltration process.The degree is similar,the difference between the two is not obvious;under the same process and operating conditions,PVDF membrane flux attenuation is much greater than the PAN membrane;water quality conditions have a greater impact on the ultrafiltration membrane flux of various processes,turbidity affects the membrane to some extent The relative flux shows that the higher the turbidity,the slower the flux decay;(3)The relationship between FI and turbidity is closely related,showing the increase of turbidity in inlet water and the trend of FI decreasing.The FI value of PVDF membrane and PAN membrane in suspended clarification ultrafiltration process and between kaolin The Pearson correlation coefficient was-0.826 and-0.811,showing a strong negative correlation.The other two ultrafiltration combined process ultrafiltration membranes are also negatively correlated,but the correlation is not strong;the total resistance is ranked in the order of suspension clarification ultrafiltration process< coagulation sedimentation ultrafiltration process<direct ultrafiltration process,PVDF membrane ultrafiltration process Reversible pollution resistance is the main filtration resistance,and irreversible pollution resistance is the main filtration resistance of the PAN membrane ultrafiltration combined process.(4)The turbidity and organic matter removal capacity of each ultrafiltration combined process under low temperature and low turbidity water conditions is reduced.The coagulation and sedimentation ultrafiltration process and direct ultrafiltration process have similar organic removal capacity,and the low temperature conditions can cause more serious Membrane pollution,membrane fouling degree: suspended clarification ultrafiltration <ultra-filtration coagulation sedimentation <direct ultrafiltration,the same kind of water quality conditions and membrane fouling index PAN membrane <PVDF membrane under the same process conditions.(5)The single factor evaluation method was used to compare the organic matter removal capability of the process form and membrane material.The effect of suspension and clarification ultrafiltration process on the removal of organic matter was far greater than other processes.Under the same process conditions,the effluent effect of PAN membrane was better than that of PVDF membrane.Good;PVDF membrane ultrafiltration combined process water production is far greater than the PAN membrane ultrafiltration combined process,the water production capacity of the suspension clarification ultrafiltration process is greater than the other two ultrafiltration combined process;PVDF membrane ultrafiltration combined process water production is far greater In the PAN membrane ultrafiltration combined process,the water production capacity of the suspension clarification ultrafiltration process is greater than the other two ultrafiltration combined processes,and the ultrafiltration combination will increase the operating cost under the low temperature water quality conditions.In the cost component,the proportion of drug charges is the lowest,and the proportion of film depreciation expenses is the highest.